The invention relates in general to backlight modules and in particular to backlight modules and fluorescent lamp assemblies thereof improving illumination uniformity of flat display devices.
Referring to FIG. 1, a conventional fluorescent lamp 10 comprises red, blue and green phosphors P coated on the inner surface thereof. The phosphor P is impacted by free electrons between an exhaust end E and a sealed end S of the fluorescent lamp 10 to provide illumination.
To coat phosphor P on the inner surface of the fluorescent lamp 10, first, air in the lamp tube is exhausted through the exhaust end E, and phosphor P is inhaled into the lamp tube from the sealed end S. Subsequently, air is reversely inhaled into the lamp tube from the exhaust end E to dry the phosphor P. Thus, the phosphor P is firmly adhered to the inner surface of the fluorescent lamp 10.
During fabrication, however, some phosphor P may peel off the inner surface of the fluorescent lamp 10 due to the reverse air flow, such that the phosphor P on the inner surface of the fluorescent lamp 10 is non-uniform. As shown in FIG. 1, as the phosphor P near the sealed end S is usually thicker than the exhaust end E, thus illumination of the fluorescent lamp 10 is also non-uniform.
FIG. 2 illustrates a conventional backlight module employing two fluorescent lamps 10. The fluorescent lamp 10 can be a Cold Cathode Fluorescent Lamp (CCFL) or an External Electrode Fluorescent Lamp (EEFL). As shown in FIG. 2, the conventional backlight module comprises a light guide element G with two oppositely disposed fluorescent lamps 10 on a first side G1 and a second side G2 respectively. Both fluorescent lamps 10 emit light into the light guide element G to form a planar light source.
In FIG. 2, region A is adjacent to the exhaust end E of the fluorescent lamp 10, and region B is adjacent to the sealed end S of the fluorescent lamp 10. Luminance and brightness in regions A and B can be different due to nonuniform distribution of phosphor P in the fluorescent lamp 10. Thus, the light guide element G cannot provide uniform luminance and brightness.